Device for use in reproducing sounds



TToRA/Ys R. F. ALLISON ETAL DEVICE FORK USE IN REPRODUCING SOUNDS Filed May "7, 1954 Feb. 11,1958

f8 if United States Patent O DEVICE FOR USE IN REPRODUCING SGUNDS Roy F. Allison, North Egremont, and Alan C. Macy and Marsh B. Gddings, Jr., Great Barrington, Mass.

Application May 7, 1954, Serial No. 428,208 14 Claims. (Cl. 181-31) Our invention relates to the reproduction of sound zand particularly to a novel type of baille for use with a sound radiating device, such as a loud speaker, whereby sounds of any nature, but particularly sounds of low frequency, are reproduced with high fidelity.

Batlles of the general character of our invention have heretofore been used which utilize a single air column of substantially uniform cross-sectional area throughout its length. Such a column, however, must be bulky for eicient bass reproduction. Furthermore, since the crosssectional area throughout is substantially uniform, the column is as strongly resonant at the third and fifth harmonic of the basic resonance frequency as at its fundamental frequency. This leads to tone coloration and distortion of the reproduced program.

The principal object of our invention is to produce a bathe having at least one air column therein which will be just as efficient at its fundamental resonance frequency as columns of the present type having twice the average cross-sectional area. Another object is to provide a column in which the tendency to false excitation of its harmonic frequencies will be very low. A further object is to produce a baille which will be just as eiiicient as bales of the present type but which can be enclosed in a much smaller cabinet or compartment than those of the present type.

We Iaccomplish these objects by the means described below and illustrated in the accompanying drawing in which- Fig. 1 is a front elevation view of our baille;

Fig. 2 is a rear elevation view;

Fig. 3 is a side elevation;

Fig. 4 is a top view;

Fig. 5 is a vertical section through Fig. l in a plane parallel to the front and back of the cabinet; and

Fig. 6 is a small scale view similar to Fig. 1 showing only one air column.

Referring to the drawings- Our device may consist of one or more air columns which may be enclosed in almost any type of structure `so that the column or columns, as the case may be, have a substantially greater length than the average lateral dimensions thereof.

As illustrated in the drawing, we have shown our device as comprising an elongated cabinet represented generally by the numeral 1 and which, merely for the purposes of illustration, is in the form of a rectangular prism. Such a cabinet may, for example, be formed of plywood, in which the joints are made airtight by gluing or otherwise.

While it is to be understood that we are in no sense limited to the dimensions set forth below, such a cabinet may, for example, be 3'6" high, 18" wide and 6" deep. However, it is quite essential that the cabinet enclose an air space which is substantially longer than its average cross-sectional dimension. As illustrated, the enclosed air space is three and one-half times as long as the average of its width, and depth or thickness.

In the preferred form of our invention, the enclosed air space is divided into two, tapered air columns by means of the partitions 2 and 3, and the partitions 4, 5 and 6, respectively. The column formed by the partitions 2 and 3 is represented generally by the dotted line 7 in Fig. 5, and the column formed by the partitions 4, 5 and 6 by the dotted line 8. These columns taper substantially uniformly throughout their length, and the cross-sectional area of each of said columns is very much smaller at one end than at the other and they merge with each other in their zones of larger cross-sectional area.

The front 9 of the cabinet is provided with an opening 10 forming a sound emitting port, and the back 11 is provided with an opening 12 adapted to receive a sound radiating means, such as a loud speaker, for exciting the air columns. These opposed openings are spaced longitudinally of each other, as shown at 13 and the combined areas thereof is at least 25% less than the cross-sectional areas of the columns in the zone of excitation thereof. Both of these openings communicate with said columns in their zone of merger and it will be noted that the zone in which the sound emitting port communicates is of greater cross-sectional area than the zone in which the other opening communicates.

In Fig. 6, we have shown `a bafe having only one tapered air column therein formed by the partition 14 and represented generally by the dotted line 15. Like the air columns shown in the other figures, the column 1S is generally U-shaped and tapers substantially uniformly from a cross-sectional area, which may be zero at one end, to a cross-sectional area substantially equal to the cross-sectional area of the cabinet at the other end. Like the baflles shown in Figs. l-S, the cabinet shown in Fig. 6 is provided with longitudinally spaced openings 16 and 17 in the opposite sides thereof forming sound entering and sound emitting ports, respectively, which communicate with the air column in the wider zones thereof.

It will be noted that the air columns shown in Figs. 1-5 are of dierent length which results in a smoother and more extended range of frequency response, because, instead of the single fundamental resonant peak of high amplitude which is obtained with a single column, two or more response maxima combine to produce a broad, highly damped, extended response, particularly in the extreme bass range.

It is to be understood that padding or other sound absorbing material may or may not be used within the columns.

While we have described our invention in its preferred embodiment, it is to be understood that the words which we have used are words of description rather than of limitation and that changes, within the purview of the appended claims, may be made without departing from the true scope and spirit of our invention in its broader aspects.

What we claim is:

l. A device for use in reproducing sounds and comprising a cabinet enclosing an elongated air space; and at least one partition in said cabinet forming a comparatively long, tapered air column having a cross-sectional area substantially less at one end thereof than at the other; said cabinet being provided with a first opening therein adapted to receive a sound-radiating means, and a second opening forming a sound-emitting port; said openings being in opposite sides of said cabinet and communicating with said column in longitudinally spaced zones thereof adjacent the larger end.

2. The structure set forth in claim l in which the cross-sectional area of that Zone of said column with which said rst opening communicates is smaller than the zone of said column with which said second opening communicates.

3. The structure set forth in claim 1 in which the taper of said column is substantially uniform throughout the major portion of its length.

4. The structure set forth in claim 1 in Vwhich said column is generally U-shaped.

5. The structure set forth in clai-m l in which the cross-sectional area of said column at its larger end approximates the cross-sectional area of said cabinet.

6. The structure set forth in claim 1 in which the crosssectional area of said column increases from substan tially zero at one end to approximately the cross-sectional area of said cabinet at the other end.

7. The structure set forth in claim 1 in which said air space is in the form of a substantially rectangular prism.

8. The structure set forth in claim 1 in which the combined areas of said openings is at least 25% less than the cross-sectional area of said column in its zone of excitation.

9. A device for use in reproducing sounds and cornprising a cabinet enclosing an elongated air space; a plurality of partitions in said cabinet forming a plurality of comparatively long, tapered, air columns having crosssectional areas substantially less at one end thereof than at the other and merging with each other at their larger ends; said cabinet being provided with a first opening therein adapted to receive a sound-radiating means, and a second opening forming a sound-emitting port; said openings being in opposite sides of said cabinet and communicating with said merged columns in longitudinally spaced zones thereof.

10. The structure set forth in claim 9 in which there are two, generally U-shaped columns.

l1. The structure set forth in clairn 9 in Which the taper of each of said columns is substantially uniform throughout the major portion of its length.

l2. The structure set forth in claim 9 in which the cross-sectional .area of that zone of said merged columns with which said iirst opening communicates is smaller than the zone thereof with which said second opening communicates.

13. The structure set forth in claim 9 in which the combined area of said openings is at least 25% less than the cross-sectional area of said merged columns in their zone of excitation. Y Y Y Y 14. A device for use in reproducing sounds comprising a cabinet enclosing an air space inthe formof an elongated, rectangular prism; two partitions in Ysaid cabinet having angularly Adisposed portionsdividing said air space into two elongated, tapering air columns each in the general form of a VU having the major portions of the length thereof extending longitudinally of said air space; the cross-sectional area of each of said columns being substantially smaller at one end thereof than `at the other, and tapering substantially uniformly throughout the major portion of its length; saidv cabinet being provided in one side thereof with a lirst opening adapted to receive a sound-radiating means for exciting said columns in zones. adjacent the larger ends thereof, and a second opening in the opposite Asidethereof longitudinally spaced from said first opening and forming a soundemitting port communicating with both columns; the combined areas of said openings being at least 25% less than the cross-sectional area of said columns in the zone of excitation thereof.

Johnson: publication in Radio Television News, September 1951, pages 63, 144. 

